Today an email chain I’m on, where contributors swap whacky physics theories, veered into whacky political theories. Chinese communists, one physicist insisted, are orchestrating protests that have been roiling U.S. cities. China wants to make Donald Trump look bad so he loses the election to Joe Biden, who is a Chinese puppet. Others on the chain denounced and cheered this conspiracy theory.
Seeking relief from the madness, I shut my laptop and opened The Structure and Interpretation of Quantum Mechanics by philosopher R.I.G. Hughes, a 1989 book recommended to me by a mathematician. Hughes attempts to show that the mathematics of quantum mechanics, which can seem terribly arbitrary and ad hoc, has sensible underpinnings. Although Hughes’s treatise baffles me, especially when it devolves into strings of arcane symbols, it still cheers me up.
I’ve been retreating into quantum esoterica a lot lately. Last spring, after COVID-19 ruined my summer plans, I decided to pursue a long-standing fantasy: learning, or trying to learn, quantum mechanics, math and all. The project, which at the risk of grandiosity I call My Quantum Experiment, has served as a refuge.
Occasionally, I worry that it’s irresponsible to dwell on quantum puzzles while the world is spiraling out of control. Shouldn’t I devote myself to researching and writing about COVID-19 and other problems plaguing us? The problem is, my columns on these problems have zero effect, which leaves me feeling frustrated and depressed. To counter those emotions, I binge on Netflix—I just discovered the meta comedy series Community–and on quantum mechanics.
Some physicists and philosophers, especially those seeking bestseller-hood, claim that quantum mechanics, if you squint at it from the right angle, can be spiritually consoling. For example, the uncertainty principle, and quantum randomness, supposedly demolish determinism, the idea that we are all bound by unbreakable chains of causes and effects. Far from being locked into a pre-ordained trajectory, nature is creative, open-ended, giving us ample room for free will.
But the comfort I derive from quantum mechanics stems not from its feel-good implications but from its obscurity, even opacity. I enjoy being immersed in abstractions of abstractions, the meanings of which elude me. As I struggle to grasp eigenvectors or Hermitian operators, the real world and its troubles fade into insignificance. And every now and then I think I’m getting somewhere, which gives me a fleeting thrill.
Hughes gave me that feeling when he implied that the Pythagorean theorem, plus probability theory, lie at the heart of quantum mechanics. This suggestion reminded me of a lecture in which computer scientist Scott Aaronson calls quantum mechanics just a “generalization of probability theory.” Many physicists fail to appreciate this fact, Aaronson says, because they have been poorly taught. Courses on quantum mechanics usually retrace its historical development, during which physicists devised “a complicated patchwork of ideas” to account for experimental anomalies like the blackbody paradox. Aaronson continues:
Today, in the quantum information age, the fact that all the physicists had to learn quantum this way seems increasingly humorous. For example, I’ve had experts in quantum field theory — people who’ve spent years calculating path integrals of mind-boggling complexity — ask me to explain the Bell inequality to them. That’s like Andrew Wiles asking me to explain the Pythagorean Theorem.
Andrew Wiles is the mathematician who proved Fermat’s last theorem in the 1990s, and the Bell inequality is a mathematical proof related to a quantum paradox called nonlocality. Hughes and Aaronson both suggest that quantum mechanics, in spite of its daunting reputation, is conceptually simple, as simple as the Pythagorean theorem, which I learned in my childhood.
These epiphanies never last. As I keep reading, I lapse back into befuddlement, or, at best, a dim quasi-comprehension that eggs me on. Moreover, reality keeps intruding on my quantum reveries. That happened recently when, eager for fresh air, I stuffed a quantum textbook, a notebook and a collapsible chair in my backpack, pulled on a face mask and left my 11th floor apartment.
The elevator stopped a few floors below mine, and a young man in a muscle shirt stepped on, wearing no mask. I said, You can’t get on without a mask. Glaring at me, he pulled a mask from his pocket and pulled it over his face, saying, Happy? Before he stepped on the elevator, this guy was in a superposition of states. But as soon as we interacted, his wave function collapsed into jerkitude.
My blood was still boiling when I arrived at a park near my building, a grassy pier that juts into the Hudson River. I found a shady spot between several chattering young families and assembled my collapsible chair. Soon I was so struggling so mightily to comprehend wave functions that I forgot about the jerk on the elevator and the conspiracy theorists on my physics list.
I occasionally looked up from my book to glance at the Hudson, its surface crisscrossed by waves, and at the exuberant moms, dads and kids around me. It was the kind of sunny, sparkly day that makes it hard to imagine all the misery out there, all the anger and fear.
I thought, What if you could construct a wave function for the United States? What would it show? We would be suspended in a superposition of many states, from okay to very, very bad. The Presidential election will serve as a test, a measurement, that collapses the wave function of America and reveals who we really are. Then more than ever, I may need to retreat into My Quantum Experiment.
Richard Feynman warned against trying to understand quantum mechanics. “Do not keep saying to yourself, ‘How can it be like that?’”, he said, “because you will get ‘down the drain,’ into a blind alley from which no one has escaped. Nobody knows how it can be like that.” Hughes and other sages reject Feynman’s stance as defeatist. I find it heartening. I like the thought of slipping down the drain of a bottomless mystery as the world collapses over and over again around me.
John Horgan directs the Center for Science Writings at Stevens. This column is adapted from one originally published on ScientificAmerican.com.
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